Converting To EFI With FAST EZ-EFI

When you think of hot rodding, old carburetors, and high horsepower you don’t necessarily think of great gas mileage or, for that matter, easy starting on those cold mornings. Now, when you think of aftermarket fuel injection most of us picture complicated wiring diagrams and countless hours of programming with a laptop. Well, with Fuel Air Spark Technology’s (FAST) EZ-EFI fuel injection kit they took the guesswork out of the otherwise electrical engineer’s job and put it into a complete plug-and-play package. The kit comes complete with everything you need to convert your motor from carburetion to fuel injection in a few hours, depending on your skill level. The only thing the kit does not include is a way to hook up the fuel return line to your gas tank, but we’ll show you a few options on how to do that.

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So why would you want to spend the extra coin to remove your carb when it works just fine? Well, for starters let’s look at starting and driveability. Have you ever tried to start your truck on a cold morning and it just seemed to not want to? Or worse yet, have you driven to a significantly higher or lower elevation and now your carb jetting is too lean or rich causing poor driveability? So, how does the FAST EZ-EFI fix this?

Well, there are sensors that fine-tune the vehicle’s fuel delivery to enrich or lean out the fuel mixture ever so slightly. The manifold absolute pressure (MAP) sensor’s main job is to detect and measure the engine’s load. The throttle position sensor (TPS) tells the ECU when the throttle is opened or closed and also takes the place of a carburetor’s accelerator pump. The intake air temp (IAT) sensor helps the ECU determine the air density and helps to adjust the amount of fuel that is given to the motor. If the air density becomes less dense then the ECU will decrease the amount of fuel, otherwise the engine would run rich and eat up gas. The O2 sensor’s job is to help fine-tune the fuel trim by measuring the amount of oxygen exiting the exhaust. If the O2 sensor reads a lean condition (15:1 or greater air/fuel ratio) then it can add a slightly longer pulse width to the injector to add a small amount of fuel to richen the mixture up. A rich condition (12:1 or less) can be fixed too, the O2 sensor will read the lack of oxygen in the exhaust and tell the ECU to decrease the amount of fuel by shortening the fuel injector’s pulse width. The rpm signal is picked up off your coil, aftermarket ignition box, etc., and helps the ECU determine the amount of fuel by calculating all the sensors’ data together, extremely fast.

So, why should I care about fuel control when my carbureted motor is running just fine? Well, without getting into a heated discussion about carbs versus EFI, let me ask you this: Do you know what fuel mixture your vehicle is running? Without an O2 sensor in the exhaust, or dyno time, you could be running your motor really rich, or worse, dangerously lean. Chances are that your carbed motor is running rich. While a little rich is not all a bad thing, too much fuel in the mixture can cause pre-detonation, poor mileage, fuel in the oil, black smoke, bad smells, carbon deposits, fouled plugs, and fuel-washing the cylinder walls, causing lubrication problems. Although the previous examples are the extremes of running an engine way too rich, the majority of us are just looking for a few more miles per gallon.

On the way into work I was thinking about gas prices here in California, which average about $4.20 a gallon, with premium about 20 cents higher. Let’s just say the average classic truck guy drives 5,000 miles per year with premium gas at $4.40 a gallon and gets an average of 12 miles per gallon while running a carb that is way too rich. This means that the fuel cost is $1,833 per year. Now, if you pick up just a few mpg, say from 12 to 16 you can cut that fuel cost down to $1,375 per year. Now, I can’t say what your fuel mileage can or can’t be because there are just way too many factors that come into play, like how heavy your right foot is or the condition of your motor, but more than likely you should be able to pick up some mpg savings at the pump.

One of the cool things we are able to show with this swap is that during a single day my 383 motor (“Junkyard Heap,” Jul. & Aug. ’11) was first dynoed with a tuned 750-cfm carb and then dynoed again after the EZ-EFI was swapped on. The motor with the carb did very well, with an output of 454.6 hp and 481 lb-ft of torque. We ran the motor on Westech Performance’s Super Flow dyno, which has the ability to change the coolant temp using the giant water tank just outside the dyno room. For the motor with the carb we ran at 130 degrees, but when we swapped to the EZ-EFI the ECU didn’t want to go into closed loop until 170 degrees. This meant that the system didn’t want to fine-tune until then. With the increased coolant temp we expected to lose a lot of power, but after the EZ-EFI went through the tuning process we only dropped 5 hp and 5 lb-ft. My personal opinion is that we could have improved the overall dyno numbers by running the motor in different parameters to help the computer learn different fuel calibrations that could have made numbers better than what we achieved with the carb. Driving the FAST EZ-EFI in more than one condition will enable the system to continuously learn and fine-tune itself for optimal performance. I was highly impressed with the dyno numbers and can’t wait to see what this system does once the engine is installed in the truck. CT